Apex domains cannot have CNAME records.
Question and response
Question
dig maildata.it. NS
Answer
maildata.it. 2 NS ns2.mvmnet.com.
maildata.it. 2 NS ns4.mvmnet-dns.eu.
maildata.it. 2 NS ns1.mvmnet.com.
maildata.it. 2 NS ns3.mvmnet.it.
Authority
The response has no authority records.
Additional
ns1.mvmnet.com. 2 A 94.143.154.34
ns2.mvmnet.com. 2 A 94.143.153.34
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0